Tool revolver unit for a machine tool

ABSTRACT

A tool revolver unit for a machine tool for machining workpieces, having a housing ( 1 ) and a tool disc rotatable relative thereto about an axis ( 3 ), and having a rotary drive ( 13, 15 ) for a rotational motion of the tool disc, and additionally having a further rotary drive ( 19, 23 ), is characterized in that the further rotary drive ( 19, 23 ) is a servomotor for controlling a locking device ( 5, 31, 37 ) enabling a releasable rotary lock between the housing ( 1 ) and the tool disc.

The invention relates to a tool revolver unit for a machine tool for machining workpieces, having a housing and a tool disk that can rotate around an axis relative to this housing, having a rotary drive for rotation of the tool disk and having another rotary drive.

A tool revolver unit of this type is already known from document DE 10 2005 021 202 B3. In this known solution, a rotary drive drives the tool disk via a rotating element of the revolver to place the latter in a rotational position that is provided for machining with a respective machining tool that is arranged at the tool disk. The additional rotary drive makes it possible to drive via a shaft a rotating tool that is optionally attached to the tool disk.

During the operation of such tool revolver units, especially when turning operations are performed with a tool that is rigidly attached to the tool disk, high stresses occur with correspondingly high torques, which attempt to rotate the tool disk out of the required position. To ensure a high-grade machining, special measures are therefore necessary which make possible a reliable immobilization of the tool disk in the required rotational position.

In the above-mentioned known solution, a brake assembly that can be activated hydraulically is provided for this purpose, said brake assembly producing a holding torque on a brake disk by pressing a brake lining. When high stresses occur, this makes it impossible to ensure secure holding in position of the tool disk.

To this end, it is already known, in the case of movable units of similar type that carry machining tools, to ensure the positional immobilization of the component that carries the tool by means of a positive locking engagement of locking elements that are equipped with a Hirth coupling, whereby such immobilizing devices can also be activated hydraulically, see, for example, document DE 39 13 139 C2.

The use of a catch via elements equipped with a Hirth coupling avoids the drawbacks that exist in the above-mentioned known solution by inadequate holding torques of the brake assembly; in the known solutions with fluid-activated toothed elements with Hirth couplings, however, the drawbacks of high cost and large space requirement for pressurized spaces, fluid lines, fluid connections, etc., have to be accepted.

To this end, the object of the invention is to make available a tool revolver unit that, with an especially compact design, simultaneously ensures an especially secure positional immobilization of the tool disk, even when high stresses occur.

According to the invention, this object is achieved by a tool revolver unit which has the features of claim 1 in its entirety.

Accordingly, one essential peculiarity of the invention is the additional rotary drive, which is present in addition to the rotary drive that is used in the positioning of the tool disk, is used as a servomotor of a locking device for the releasable rotary lock between the housing and the tool disk. In that, instead of a brake assembly, a locking device for the tool disk is provided which, on the one hand, affords the advantage that in comparison to a location fixation by means of a holding torque produced by a brake assembly, perfect positional fixing in the locking state is achieved. On the other hand, the motorized activation of the locking device makes possible an essentially simplified and extremely compact design, compared to conventional, fluid-activated locking devices.

The two rotary drives can be electric-motor drives that consist of rotors and stators.

In an especially advantageous way, the arrangement here can be made so that both rotary drives are external rotor motors, whose rotors are arranged concentrically to one another and to the axis of rotation of the tool disk. This coaxial arrangement, relative to the axis of the rotation of the tool disk, not only opens up the possibility of an especially simple direct drive of the tool disk, by the rotor of the pertinent external rotor motor undergoing transition directly into a drive shaft of the tool shaft, but also makes possible an especially slim configuration of the housing.

When using electric motor drives that consist of rotor and stator, a sensor-free positional determination of the rotor in question can be provided conventionally, for example with use of control devices and methods of the type that disclosed in, for example, document DE 103 33 414 A1. No additional space is required within the housing. Rather, the control device that is connected via an interface to the machine control can be mounted outside of the housing and connected to the pertinent external rotor motor in the housing only via three-phase connecting cables.

The locking device that can be activated by means of the additional rotary drive that is used as a servomotor preferably has toothed elements with a Hirth coupling, which can be brought in and out of toothed engagement with each other by relative movements carried out in the axial direction, so that especially secure rotational locking can be achieved by being in toothed engagement, as is also the case in conventional, fluid-activated securing devices with Hirth couplings.

In an especially advantageous way, the arrangement can be made so that the rotary drive that is used here as a servomotor of the locking device is connected to a control gear that transforms the rotation produced by the servomotor into an axial displacement of a toothed element that is equipped with a Hirth coupling.

The control gear can have a cam ring with a control curve that is connected to the rotor of the associated rotary drive and is mounted rotatably and axially immovably in the housing; during rotation, an axial stroke of the movable toothed element of the locking device guided thereon can be produced via said control curve.

In especially advantageous embodiments, which are distinguished by an especially compact design, the arrangement is made such that the control curve forms a track that is concentric to the shaft; on said track are guided rollers of the axially movable toothed element that forms a locking ring; said rollers form cam sensing devices.

Preferably, there is a prestressing device on the locking ring that holds the rollers in contact with the control curve of the cam ring by friction, and said prestressing device prestresses the locking ring for an axial movement that runs from the locking position into the unlocking position of the locking device. The locking device is thus designed mechanically resettable.

In an especially simple and advantageous way, the prestressing device can have at least one compression spring arrangement that, extending through the Hirth coupling of the locking ring, is clamped between the latter and a corresponding axial and movable toothed element of the locking device and produces the axial prestressing of the locking ring.

The locking device can be configured so that in addition to the locking ring, there are two toothed elements, specifically a rotatable ring that forms the actual revolver rotating element that is connected to the tool disk as well as a ring that is integral with the housing and that surrounds the latter on the outer peripheral side, whose Hirth couplings are in each case in a radial plane and can engage with the Hirth coupling of the locking ring.

Below, the invention is explained in detail based on an embodiment that is depicted in the drawing. Here:

FIG. 1 shows a diagrammatically simplified longitudinal section of the housing of an embodiment of the tool revolver unit, the operating state in which the locking device for rotary locking of the tool disk in the locking position is located being shown in the part located above the longitudinal shaft in the drawing, while the operating state of the unlocking position of the locking device is shown in the drawing part located below the longitudinal shaft.

FIG. 2 shows a perspective view, enlarged compared to FIG. 1, of only one locking ring of the locking device of the embodiment, and

FIGS. 3 and 4 show perspective partial views, on an enlarged scale compared to FIG. 2, of only a partial area of the locking device in the angle cut view, FIG. 3 showing the operating state of the unlocked locking device and FIG. 4 showing the operating state of the locked locking device.

The embodiment shown in diagrammatic form in longitudinal section in FIG. 1 has a more or less cuboid-shaped housing 1, whose longitudinal shaft 3, which is positioned eccentrically, forms the axis of rotation for a front-side toothed elethent 5, which on its outside forms the receiver for an adjustable tool disk, not shown, at desired rotational positions. The toothed element 5 is a ring element that is mounted to rotate in the housing 1 and that is provided on its end that is inside the housing with a Hirth coupling 7 that is concentric to the shaft 3. The toothed element 5 is screw connected, only one screw 9 being shown, to a hollow shaft 11 so as to be able to rotate, the bell-like end section of said hollow shaft forming the rotor 13 for an external rotor motor that is concentric to the shaft 3, whose stator 15 is immobilized on an engine bracket 17, which is located on the rear end area of the housing 1. The stator 15 can be supplied with current by a conventional position-regulating device, not shown, to adjust the toothed element 5 in selected rotational positions via the hollow shaft 11, positions in which the tool disk that is fastened to the toothed element 5 occupies the rotational position that is provided for the desired machining process.

Coaxially to the external rotor motor that is formed from rotor 13 and stator 15, there is a second rotary drive that is coaxial and concentric to the axis of rotation 3, which is closer to the front side, i.e., the toothed element 5. The second rotary device is also an external rotor motor with a rotor 19 that is concentric to the axis of rotation and that surrounds a stator 23 like a bell that is immobilized on a carrier 21 that is integral with the housing. On its end section that faces the toothed element 5, the rotor 19 undergoes transition into a cam ring 25, which has a shaped piece on its end facing the toothed element 5, and forms the control curves 27, whose cam profile makes it possible to produce an axial stroke from cam sensing devices guided on the control curves 27, in which there are rollers 29. Further details of this cam control are specified below with reference to the FIGS. 2 and 4. The cam ring 25 in interaction with the rollers 29 form a control gear, by which, based on a rotation of the rotor 19 and thus the cam ring 25, an axial displacement of a locking ring 31 that is concentric to the hollow shaft 11 can be produced, on which the rollers 29 are mounted. This locking ring 31 has a Hirth coupling 33 on its end that faces the Hirth coupling 7 on the toothed element 5, which is in engagement with the Hirth coupling 7 at the toothed element 5 in the axial position, which forms the locking position, shown in FIG. 1 above the shaft 3.

In this locking position, the Hirth coupling 33 of the locking ring 31 is not only in engagement with the Hirth coupling 7 at the toothed element 5, but simultaneously with a Hirth coupling 35 that is concentric thereto at another toothed element 37, which is screwed tightly to the housing 1 and forms a ring element that is L-shaped in cross-section. In this locking position that is shown above in FIG. 1, positive locking is thus formed by the locking ring 31 between the toothed element 37 that is integral with the housing and the toothed element 5 that can be rotated with the tool disk, while in the unlocking position shown below in FIG. 1, the Hirth couplings 7, 33, and 35 are not engaged, so that a rotation of the toothed element 5 that is produced by means of the external rotor motor 13, 15 and thus of the tool disk can take place.

In an enlarged view, FIG. 2 shows details of the locking ring 31 with the rollers 29 that are mounted to rotate on it, the front-side Hirth coupling 33 as well as the control curves 27 on the cam ring 25 that is shown only partially. As can also be seen from FIG. 2, the locking ring 31 is provided with a prestressing device, which holds the rollers 29 by friction adjoining the corresponding control curves 27 and attempts to push the Hirth coupling 33 out of engagement with the Hirth couplings 7 and 35 of the toothed elements 5 or 37. As is to be seen, this prestressing device has axially movable compression pieces 39 that, extending through the Hirth coupling 33, are prestressed by compression springs 41 and are supported against the Hirth coupling 35 of the toothed element 37. As a result, the locking ring 31 comes into the unlocking position when a back rotation of the cam ring 25 is carried out, for example by supplying current to the stator 23 of the external rotor motor 19, 23.

FIGS. 3 and 4 illustrate the positions of the toothed elements 5, 31 and 37, which form the locking device, to each other. FIG. 3 shows the unlocking position, in which the rollers 29 are located in the deeper areas of the control curves 27, so that the Hirth coupling 33 of the locking ring 31 is both out of engagement with the Hirth coupling 35 in the toothed element 37 that is integral with the housing and out of engagement with the Hirth coupling 7 at the rotatable toothed element 5.

In comparison, in the locking position shown in FIG. 4, the rollers 29 have run up onto the elevated curve areas 42 of the control curves 27 so that the Hirth coupling 33 of the locking ring 31 is in engagement with both with the Hirth coupling 35 of the stationary toothed element 37 and with the Hirth coupling 7 at the rotatable toothed element 5. As FIGS. 3 and 4 also illustrate, the tooth shapes of the interacting Hirth couplings 7, 33 and 35 are selected such that, when they are in engagement, the toothing generate torques producing an alignment, and thus smooth toothed engagement is ensured.

As can be seen from FIG. 1, the hollow shaft 11 is in the area in which it forms the rotor 13 of the rotary drive for the adjustment of the tool disk, mounted in the housing 1 via roller bearing 6. The rotor 19 and the cam ring 25 of the locking device that is connected to the latter are mounted to rotate via roller bearing 8. 

1. A tool revolver unit for a machine tool for machining workpieces, having a housing (1) and a tool disk that can rotate around an axis (3) relative to the housing, having a rotary drive (13, 15) for rotation of the tool disk and having another rotary drive (19, 23), characterized in that the other rotary drive (19, 23) is provided as a servomotor for controlling a locking device (5, 31, 37) that enables releasable rotational locking between the housing (1) and the tool disk.
 2. The tool revolver unit according to claim 1, characterized in that both rotary drives are electric-motor drives that consist of rotors (13, 19) and stators (15, 23).
 3. The tool revolver unit according to claim 2, characterized in that both rotary drives are external rotor motors, whose rotors (13, 19) are arranged concentrically to one another and to the axis (3) of rotation of the tool disk.
 4. The tool revolver unit according to claim 1, characterized in that the locking device has toothed elements (5, 31, 37) with a Hirth coupling (7, 33, 35), which can be brought in and out of toothed engagement by relative movements that take place in the axial direction.
 5. The tool revolver unit according to claim 4, characterized in that the other rotary drive (19, 23) that is used as a servomotor of the locking device is connected to a control gear (25, 27, 29) that transforms the rotation produced by the servomotor into an axial displacement of an axially movable toothed element (31) that is equipped with a Hirth coupling (33).
 6. The tool revolver unit according to claim 5, characterized in that the control gear has a cam ring (25) with a control curve (27) that is connected to the rotor (19) of the associated rotary drive (19, 23) and is mounted rotatably and axially immovably in the housing (1), and during rotation, an axial stroke of the movable toothed element (31) of the locking device (5, 31, 37) guided thereon can be produced via said control curve.
 7. The tool revolver unit according to claim 6, characterized in that the control curve (27) forms a track that is concentric to the shaft (3), on said track there being guided rollers (29) of the axially movable toothed element that forms a locking ring (31), said rollers forming cam sensing devices.
 8. The tool revolver unit according to claim 7, characterized in that a prestressing device (39, 41) that holds the rollers (29) by friction in contact on the control curve (27) of the cam ring (25) is present on the locking ring (31), and said prestressing device prestresses the locking ring (31) for an axial movement that runs from the locking position into the unlocking position of the locking device (5, 31, 37).
 9. The tool revolver unit according to claim 8, characterized in that the prestressing device has at least one compression spring arrangement (41) that, extending through the Hirth coupling (33) of the locking ring (31), is clamped between the latter and a corresponding axially immovable toothed element (37) of the locking device (5, 31, 37) and produces the axial prestressing of the locking ring (31).
 10. The tool revolver unit according to claim 9, characterized in that the locking device (5, 31, 37) has a ring element (5) that can rotate with the tool disk as a first toothed element and a ring element (37) that surrounds the latter on the outer periphery side and is integral with the housing as a second toothed element, and characterized in that the Hirth couplings (7 or 35) of these toothed elements (5 and 37) in each case lie in a common radial plane and can be in engagement with the Hirth coupling (33) of the locking ring (31). 